Python重写父类的三种方法

1.基础应用

class Aniaml(object)
	def eat(self):
		print("动物吃东西")
class Cat(Animal):
	def eat(self):
		  print("猫吃鱼")
		  #格式一：父类名.方法名(对象)
		  Animal.eat(self)
		  #格式二:super(本类名,对象).方法名()
		  super(Cat,self).eat()
		  #格式三:super()方法名()
		  super().eat()
cat1=Cat()
cat1.eat()
print(cat1)

2.实际应用

#用元类实现单例模式
class SingletonType(type):
    instance = {}

    def __call__(cls, *args, **kwargs):
        if cls not in cls.instance:
            # 方式一:
            # cls.instance[cls] = type.__call__(cls, *args, **kwargs)
            # 方式二
            # cls.instance[cls] = super(SingletonType, cls).__call__(*args, **kwargs)
            # 方式三
            cls.instance[cls] = super().__call__(*args, **kwargs)
        return cls.instance[cls]


class Singleton(metaclass=SingletonType):
    def __init__(self, name):
        self.name = name


s1 = Singleton('1')
s2 = Singleton('2')
print(id(s1) == id(s2))